Method for manufacturing petroleum pitch having high aromaticity

ABSTRACT

Method of producing a pitch suitable for a binder, said method comprising bringing petroleum base residual oil into direct contact with a non-oxidative gaseous heat transfer medium to subject said oil to cracking poly-condensation.

United States Patent [1 1 Takahashi et al.

[ Dec. 23, 1975 METHOD FOR MANUFACTURING PETROLEUM PITCH HAVING HIGHAROMATICITY [75] Inventors: Ryoichi Takahashi; Takuji Hosoi,

both of Tokyo; Takaaki Aiba, Yokohama; Tsutomu Konno, Tokyo, all ofJapan [73] Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha, Tokyo, Japan[22] Filed: Aug. 22, 1974 [21] Appl. No.: 499,858

Related US. Application Data [63] Continuation-impart of Ser. No.240,619, April 3,

1972, abandoned.

[30] Foreign Application Priority Data Apr. 1, 1971 Japan 46-19230 [52]US. Cl. 208/40; 208/128; 208/130 [51] Int. Cl. C10G 9/36 [58] Field ofSearch 208/39, 40, 22, 128, 130,

[5 6] References Cited UNITED STATES PATENTS 3,318,801 5/1967 Alexanderet al. 208/40 3,617,477 11/1971 Gomi 208/22 3,692,663 9/1972 Ueda et al.3,794,579 2/1974 Enomoto et al. 3,835,024 9/1974 Ueda et al. 208/22Primary ExaminerHerbert Levine Attorney, Agent, or FirmLane, Aitken,Dunner &

Ziems [57] ABSTRACT Method of producing a pitch suitable for a binder,said method comprising bringing petroleum base residual 'oil into directcontact with a non-oxidative gaseous heat transfer medium to subjectsaid oil to cracking poly-condensation.

4 Claims, 2 Drawing Figures US. Patent Dec. 23, 1975 Sheet10f2 3,928,170

Fl G.

US. Patent Dec. 23, 1975 Sheet20f2 3,928,170

FIG.

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Temperature C METHOD FOR MANUFACTURING PETROLEUM PITCH HAVING HIGHAROMATICITY CROSS REFERENCE TO RELATED APPLICATION This is acontinuation-in-part of Ser. No. 240,619 filed Apr. 3, 1972 nowabandoned.

BACKGROUND OF THE INVENTION:

This invention relates to a method for manufacturing a a highly aromaticpitch having a softening point of l30-300C, a hydrogen/carbon atomicratio of 0.4-1.1 and 40-80 wt% fixed carbon content and, moreparticularly, to a highly aromatic pitch suitable for use as a cokemanufacturing binder.

Blast furnace coke and foundry coke are conventionally manufactured fromheavy coking coal. The heavy coking coal resource, however, is limitedand such coal is not available in abundance. To compensate for this factseveral attempts have been made to manufacture blast furnace coke andfoundry coke from a comparatively easily available weakly coking coal byadding a binder to give an adequate caking property to the weakly cokingcoal. An already proposed countermeasure is to utilize a coal pitch orpetroleum base residual oil as such a binder. Coal pitch, however, isnot available in abundance and the petroleum base residual oil, whichcontains aliphatic hydrocarbons as its principle constituents, cannot beused advantageously as a binder due to its insufficient miscibility withthe coal as well as its low coking value.

SUMMARY OF THE INVENTION:

It has now been discovered that a petroleum pitch, suitable for use assuch a binder, can be prepared by heat-treating an aliphatichydrocarbon-containing petroleum base residual oil for efficientlycracking, polycondensing and aromatizing same.

It is therefore a primary object of this invention to provide apetroleum pitch which can be used as a binder to give a caking propertyto a weakly coking coal.

Another object of this invention is to provide a heat treatment methodfor converting a petroleum base residual oil to such a petroleum pitch.

These and other objects of this invention will become apparent fromreading the following description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic flow diagramrepresenting the process of the present invention for the production ofa pitch suitable for use as a binder for low coking coals, and;

FIG. 2 shows the relationship between the partial pressure andtemperature of the vapor phase.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

The aliphatic hydrocarbon-containing petroleum base residual oil usableas raw materials for manufacturing the pitch of this invention includevarious residual oils obtained from the petroleum refinary industry(e.g., normal pressure distillation residual oil, vacuum distillationoil, thermal cracking residual oil and contact cracking slurry oil) andother various petroleum refinary residues such as Duo-sol extract,furfural extract, propane extraction residual oil, heavy crude oil, tarsand oil, shale oil and mixture of these materials.

From the point of view of economics, however, those materials whichcontain more than by weight of constituents having 350C or lower boilingpoints are not preferred. Desirable raw materials are residual oils suchas, for example, a vacuum distillation residual oil which is in a solidor semi-solid state at normal temperatures.

However, these petroleum base residual oils have heretofore found noextensive usage other than as fuel and road-paving material. Moreover,the use of these petroleum base residual oils as fuel has been inhibitedbecause the combustion of these oils which have a high sulfurconcentration produces sulfurous acid gas and results in atmosphericpollution. On the other hand, the demand for road-paving petroleumresidual oils in recent years has increased at a much slower pace ascompared with the increase in production and supply of these petroleumresidual oils which has accompanied the increase in production ofpetroleum products and petrochemical products. This is regarded as aserious problem which might impede the future development of thepetroleum refinary industry.

In consideration of this problem together with the actual problem thatthe coking coal is in short supply for manufacturing blast furnace coke,attempts have been made to manufacture artificial coking coal frompetroleum base residual oils. The primary purpose of these attempts iscommonly to provide a substitute for natural coking coal. Practicaldifficulties encountered in these attempts are that the resultingproducts are expensive due to the low yield thereof, the resultingproducts have a considerably large sulfur content and that the rawmaterials for manufacturing such artificial coking coals have only anarrow selectivity.

The petroleum pitch prepared by this invention represents an advance inthe art from the viewpoint of economics and the conserving of naturalresources. The pitch prepared from a residual oil such as petroleumasphalt by converting the chemical structure and composition thereof hasan excellent caking or binding effect and hence,

1. By adding a small quantity of the pitch to 'a coke manufacturingblended coal, a high quality blast furnace coke can be prepared;

2. The pitch of this invention greatly saves heavy coking coals fromuse, of which future availability, judging from its limited deposit,seems to be limited, and yet allows the production of high quality coke;and

3. By blending the pitch with a non-coking coal or weakly coking coalhaving no or a little caking property, a quality coke comparable tothose prepared from heavy cokingcoals can be produced.

According to this invention, the pitch is prepared by treating apetroleum base residual oil with heat. The heat treatment of thisinvention may be conducted in such a manner that the raw material oil isbrought into direct contact with a non-oxidative gas or a perfectlycombusted gas containing substantially no oxygen, as a heat carrier gas,heated to 400-2000C. Suitable nonoxidative gases used in this inventioninclude nitrogen, argon, steam, hydrogen and hydrocarbon gas.

To effect thermal cracking, aromatization and polycondensation smoothlyand to prevent the production of undesirable coke by eliminating thedanger that the raw material oil will be locally over-heated by the heatcarrier gas, it is necessary to maintain the temperature of raw materialoil within the range of 350450C which is lower than the above-mentionedtemperature of heat carrier gas. To make the heat carrier gas bring intodirect contact with the raw material oil, the heat carrier gas may bedistributed into a continuous phase of the raw material oil. For thispurpose the heat carrier gas may be blown into the raw material oil or,alternatively, a jet scrubber may be employed advantageously for thegas/liquid contact. In either case the reaction may be effectedadvantageously either batchwise or in a continuous manner.

The pressure in the reaction vessel should be less then 3.0kg/cm (gauge)and the dwell time for the reaction should be within the range of from0.5 to 20 hours, preferably from 0.5 to hours.

The heat carrier gas used in the present invention serves as heat sourceand further serves greatly in stripping the oil produced by cracking.Such action of the heat carrier gas aids in producing a pitch havingdesirable properties as binder.

The heat treatment of this invention may be conducted as summarizedabove, or the raw oil may be also preheated prior to the above-describedheat treatment. The preheating stage may be operated by heating the rawoil to an elevated temperature by external or internal heating means fora short time or by a combination of such means, or alternatively, byheating the raw oil in a tubular heating system for a short time.Thereafter the preheated raw oil is flashed into the reaction vessel toeffect the heat treatment.

Of the above, the preheating procedure using the tubular heating systemis most effective because the raw oil can be efficiently and quicklybrought up to an elevated temperature. In this embodiment, the raw oilis preferably passed through the tubular furnace with a dwell timewithin the range from 05-15 minutes so that the temperature of the rawoil at outlet of the tubular furnace will be within the range from 450to 520C and the pressure at the outlet will be within the range from 0to l50kg/cm (gauge). The thus preheated raw oil flashes upon enteringthe reaction vessel.

In the preheating stage, the decomposition of the raw oil occurs to someextent but the poly-condensation reaction to only a negligible extent.Thus, the preheating stage has no adverse influence on the subsequentheat treatment of this invention.

The technical principles of the heat treatment of this invention are asfollows:

1. A certain amount of heat sufficient to complete reaction of the rawmaterial oil is supplied to the raw material oil by bringing a hightemperature gaseous heat transfer medium into direct contact with alarge quantity of raw material oil;

2. That portion of the raw material oil which is unstable at hightemperatures is cracked and the cracked oil is separated from the pithfraction by the stripping action of the gaseous heat transfer medium;and

3. A pitch having the desired properties is prepared from that portionof the raw material oil having comparatively good heat stability byholding said portion under not too severe temperature conditions for anextended period of time.

A thermal cracking of the raw material residual oil cannot be effectedwithout being accompanied by thermal polycondensation. A structuralmodel of vacuum distillation residual oil may be a cyclic structurewhich is aromatic and/or alicyclic carrying one or more long aliphaticside chains. When such a vacuum distillation residual oil is used as araw material, in an early stage of the heat treatment thereof a crackingof the side chain will occur at certain temperatures but no remarkablepolycondensation reaction. As the oil fraction mainly consisting of thecracked aliphatic compounds is stripped from the liquid phase by thegaseous heat transfer the ring concentration will increase and thepolycondensation will become more and more conspicuous. The numericalexpression of the degree of cracking may be possible by measuring thedistilled oil fractions, whereas the numerical expression of the degreeof polycondensation may be obtained by a solvent test, that is, bymeasuring the weight percentage of the portion insoluble in standardsolvents such as heptane, benzene, quinoline, etc. To prepare a pitchhaving a softening point above C, for example, the polycondensation mustbe allowed to proceed to a considerable degree. This may readily beunderstood by numerically expressing the degree of reaction. The degreeof reaction may be expressed in terms of a non-dimensional numericalvalue k6 where k is a function of temperature and the reaction velocityconstant (l/sec) determined on the supposition that the cracking is areaction of the first order and 0 is the reaction time (sec). Whenexpressed in terms of k0, where k6 has a relatively small value, thereaction takes place mainly in the form of cracking and, underconditions where k0 has a larger value, the reaction takes place mainlyin the form of polycondensation.

According to this invention the thermal cracking and thermalpolycondensation of the raw material residual oil may be considered tobe classified into two sequential steps:

First Step: Under conditions of k9 is a(wherein, while a varies with thetemperature of heat transfer gas, it is a value of approximately 2.0 incases where the temperature of heat transfer gas is less than 850C), themain reaction proceeds in the form of a cracking of the side chains andthat cyclic portion which is cracked easily, but no marked degree ofpolycondensation takes place. Therefore, the manner of reaction has nospecial importance and the raw material oil may be heated either by useof an externally heated tube or by making the raw material oil come intodirect contact with a heat carrier.

Second Step: Under conditions of k6 a(wherein a has the same meaning asthe above), the following two reaction conditions are essential:

A. The liquid phase should not be overheated during reaction but shouldpreferably be maintained lower than 450C. This is because an excessivelyhigh temperature will result in a drastic polycondensation reaction andincrease of the mesophase, which necessarily develops in the cokingprocess. As a result, the liquid phase will not form a pitch suitablefor use as a binder. The term mesophase as used herein means a type ofliquid crystal which develops when the pitch is heated to approximately400C. The mesophase consists of pitch-composing molecules having anaromatic structure which have through the interaction associatedtogether through the interaction as anisotropic spherules, as isvisually observable by use of a polarizing microscope. When heated tohigher temperatures, the mesophase liquid crystals grow larger andcombines with adjacent crystals to form a larger mesophase, which may beregarded as a precursor of coke.

B. The conditions required for stripping the oil cracked in said firststep from the liquid phase (pitch phase) must be carefully selected.These stripping conditions are selected in accordance with the partialpressure and temperature of the vapor phase. The relationship betweenthe partial pressure and temperature is as shown in FIG. 2. The partialpressure of vapor phase as used herein means the total partial pressureof the cracked gas and the oil vapor in the heat transfer gas(hereinafter, the partial pressure of vapor phase is expressed'as'Porg.). The critical partial pressure may be 5 mmHg at 300C, andpreferably lower than 3 mmI-Ig, because if the reaction proceeds underconditions where more volatile cracked oil remains in the liquid phase(or pitch phase), then the mesophase will grow large even attemperatures lower than 450C and coking will take place to a largeextent, giving a reaction product in the form of a mixture of coke andoil but not a pitch. This suggests that the reaction need be effected attemperatures at which the liquid phase (pitch phase) has a considerableviscosity. When the liquid phase has too low a viscosity, agglomerationof mesophase will occur easily to form coke but not pitch.

The equation representing the upper curve of FIG. 2 is as follows:

Porg(mmHg) 1.03 X X e Hm wherein T is the temperature (C) of the liquidphase in the reaction zone.

In the second step and, especially, under conditions where k0 becomeslarge enough, the reaction will proc'eed mainly in the form ofpolycondensation. Therefore, to prepare a pitch, and especially a pitchsuitable for use as a binder, adequate precautions have to be made toeliminate the danger that agglomeration of the mesophase will occur. Forthis reason, when the reaction has to be effected at relatively lowtemperatures and under normal or elevated pressures, the reaction mustbe conducted over a comparatively long period of time while introducingan increasingly larger amounts of steam.

By means of the present invention, the heat energy required toefficiently treat one weight unit of the raw material oil can be reducedremarkably, generally to an amount as low as 1/10 of that required byany conventional method employing a cracking furnace of the internalheating type. This is because the heat energy supplied to the reactionsystem by the heat transfer medium results in the thermal cracking ofraw material oil and the free radicals produced by thermal crackingserve as initiators for the polycondensation and aromatization reactionsof the molecules within the liquid phase. This permits the desiredreaction to proceed smoothly in the liquid phase under not so severetemperature conditions and promotes the distillation of by-product oilfractions.

The preferred reaction conditions as mentioned previously were foundexperimentally. The lower temperature limits for the heat transfer gasand the raw material represent, for example, the lowest temperatures atwhich the reaction can proceed economically; whereas the uppertemperature limits for the heat transfer gas and raw material oil havebeen established with the purpose of restraining the undesirable cokingphenomenon and/or maintaining the stripping conditions above a certainleveLTheflow rate of the heat transfer gas is selected in accordancewith the reaction temperature. If the operating parameters are properlyselected, the

distilled oil fraction and residual pitch fraction will have apredetermined and controlled chemical structure and composition.

The pressure of reaction system will be controlled at or near normalatmosphere. A slight increase (less than 3 kg/cm G) or reduction inpressure may serve to help the reaction or separation proceed smoothly.The internal temperature of the reaction system may be maintained withina predetermined range by heating it externally.

Now the process for industrially producing the pitch of this inventionwill be described with reference to FIG. 1. The raw material oil storedin a tank 1 is-fed by a pump 2 into a preheating and cracking furnace 3,where it is preheated and subjected to a cracking process. The crackingfurnace 3 may be a tubular oven or an externally heated type. To preventcoking from occuring within the heating tube and to reduce the sulfurcontent of the product, hydrogen or volatile hydrocarbons such as, forexample, a portion of the more volatile oil distilled from the processmay be introduced at 4. Valve 5 is provided to control the pressurewithin the preheating and cracking apparatus.

The raw material which has been preheated or cracked in the first stepis then introduced into a reaction vessel 6, where the raw material issubjected to a cracking process of the second order and the cracked morevolatile fractions (gas and oil fractions) and pitch are separated. Ahigh temperature heat transfer medium is introduced through nozzle 8into the reaction vessel as a heat source and also as a stripping mediumfor the distilled fractions.

The cracked gas and distilled fraction which have been stripped withinthe reaction vessel 6 are fed through a line 9 into a fractionator l0and overhead drum 11 and further separated into a gas 12, more volatileoil 13, condensed water 14, and residual oil 15 according to theconventional procedure. The pitch fraction obtained in the reactionvessel 6 is fed through a line 16 onto a cooling belt 17 to form thepitch product 18.

As will be understood from the foregoing, the process of this inventionis either a modified visbreaking process or a modified delayed cokingprocess or, otherwise, a combination of these processes. The gaseous andoily byproducts are separated either by flashing or by variousdistillation methods.

As mentioned previously, the petroleum pitch, which is obtained byheat-treating an aliphatic hydrocarboncontaining petroleum base residualoil for crackinglpolycondensation and aromatization, is characterized bythe following properties:

Softening point: l30-300C Fixed carbon: 40-80 wt% I-l/C ratio: 0.4l.l

Of these values the softening point measured by use of a Koka type flowtester (manufactured by Shimazu Seisakusho, Ltd., Kyoto, Japan) is thetemperature at which a lg sample started to flow through a nozzle of [mmdiameter under a pressure of 10 kg/cmand at a heating rate of 6C/min.The weight percentage of fixed carbon was measured in accordance withJIS-K-242l (l966). The I-I/C ratio was determined by an elementaryanalysis.

The petroleum pitch having these properties is obtained from a petroleumbase residual oil by converting 7 the chemical structure and compositionof its main constituents by heat treatment. The petroleum pitch is richin aromatic hydrocarbons and has a remarkably improved coking value andaffinity with coal. Thereverted to products of high economic value suchas fuel oil of low sulfur content, lubricating oil and gasoline.

The scope and applicability of this invention will be more fullyillustrated by the following working examfore, addition of the pitchprepared by this invention to ples. a weakly coking coal Wlll greatlyincrease the cracking EXAMPLE 1 property of the coal, resulting in acoke having a drum index comparable with the coke obtained from a heavy6 g of Vacuum (llStlllfitlOh residual 011 from K a i coking coal. crudeoil (having the properties listed in Table l) was The blending ratio ofthe pitch of this invention with 10 placed in a reaction tank q pp hmixer, heater the weakly Coking Coa a ies depending on the type of andcooler. A gaseous heat transfer medium, preheated coal. When 50 parts ofpitch is blended with 50 parts of 10 e eleveted temperature, was thenInjected the Australian weakly coking coal (Newdell), the resulting Oilin the liquid p s n the per r ma in Coke ill ha e drum index (Dl of91.4; when 1 part constant. Table 2 gives the operating conditions andof pitch is blended with 40 parts of Australian quasithe materialbalances for three runs, and coking coal, 40 parts of Japanese weaklycoking coal P Py g different heating mediums and operating and parts ofAmerican heavy ki l, th l conditions. The properties of the products,distilled Oll ing coke will have a drum index of 91.5 (for detail, andthe P are Shown n Table 3. In these batch-type refer to the Exampleswhich follow). By adding the runs, e first p of the reaction y cracking)pitch of this invention to a raw material coal having a 20 occurs In thefi stage a the second p of the low caking property, it is possible toobtain a coke reaction y p y' e e the Second having a high qualitycomparable with the coke preg and these steps follow in a single runpared from a heavy coking coal. Table 5 lists the results of can bakingtests (box test) At an H/C ratio above 1.1, the pitch will beinsuffiwhich were conducted to determine the coking ciently compatiblewith the coal; on the other hand, at strength of the p p slmulatmg itsuse a an l-I/C ratio below 0.4, the pitch will contain increased blastfurnace This test was conducted using t pi amounts of infusibleconstituents and thus will have a Obtalhed from full 9 h term t i gtest. reduced caking property, If th it h h a lower f refers to a testmethod in which an 18 1lter oil can 15 ening point, it will be difficultto mill the pitch prior to g dwlth sample having a granular s ze thesame as mixing with the raw material coal or to stock the milled thatwhleh would be e in an Industrial Coking f pitch Without causing anyblocking. On the contrary, if nace. The results shown in Table 5 revealthat the pitch the pitch has an excessively high softening point, thenned aeeordlng t0 the present invention has excelthe pitch will containan increased quantity of infusible lent blhdlng p p r i The dlslllled01l ff0m lol constituent and present a reduced compatibility with t0 103were tested y elemental)! y l and y NMR coal. and IR spectra. Theselatter tests revealed that the If the pitch has an excessively l w fix dcarbon distilled oil products contain from 60 to 80% by weight tent,then the pitch will evaporate excessively during aliphatic hydrocarbons.The Starting matel'lali the coking process and will not produce a cokehaving Table 1 a sufficient denslty and strength. If the pitch has an Iexcessively g fixed carbon content, then the pitch Vacuum distillationresidual Oll from Khatjl crude oil will contain an increased quantity ofinfusible constitu- Specific gravity 1.032 Element analysis (a ents,presenting a reduced caking property. Moreover, g fg fg gg g s 10:41olly fractions developed as by-product in the course of Ash (wt 0) 0.05N 0.66 producing the pitch are consisted of mainly paraffin Penetratlm92 5 :38

- base hydrocarbons, therefore, they can be easily con- Table 2 Example1 Operating Conditions No. 101 102 103 Operating Heat transfer gasOxygen- Steam Nitrogen conditions hydrogen flame Heat transfer gastemperature 1500 700 500 (C) Heat transfer gas flow rate 3.2 5.0 4.2 (M/H1) Liquid phase temperature 350 430 450 Duration of operation (Min.)30 210 Material H, (wt%) 0.5 0.1 0.1 balance CH 5.2 4.8 3.3 CgHqlCgH48.8 4.4 1.2 C H +C H 7 .2 Trace 0 C Hydrocarbon 5.0 0 0 H25 2.0 2.1 1.9Distilled oil 45.3 62.5 69.8 Pitch 24.5 20.6 21.7 Loss 1.5 5.5 2.0

While the calculated value of R6 in No.10] is 0.2. effective k0 isestimated to be considerably larger than 0.2. The reason is that thetemperature within the boundary layer between the bulk liquid phase andbubble phase is considerably higher than the measured value (350C) dueto high temperature of heat transfer gas used.

Table 3 Properties of the Distilled oil product o. 101 102 103 S eclficgravity ((1 0.911 0.940 0.934 F ash point (C) 102 146 152 *DistillationInitial Boiling Point(l.B.P.) 132 211 200 test (C) distilled (C) 252 344331 50% distilled (C) 348 474 460 80% distilled (C) 475 525 520Elementary C (wt%) 86.30 84.80 85.6

analysls H (wt%) 11.08 11.88 12.15 N (wt%) 0.52 0.43 0.36 S (wt%) 2.102.26 2.32 H/C (atomic ratio) 1.55 1.68 1.71

The temperatures shown above have been corrected to represent theboiling points (C) at normal pressure.

Table 4 Properties of the pitch product Softening point (C) *250 *280*263 Fixed carbon (wt%) 62.3 75.1 67.2 Ash 0.7 0.5 0.2

Element C 86.5 87.6 87.9 analysis H 4.62 5.49 5.76 N 1.90 1.76 1.56 S6.08 6.75 6.48 l-l/C (atomic ratio) 0.650 0.752 0.786 Solvent extractiontest Benzene insoluble matter (wt%) 65.4 74.8 58.9 Quinoline insolublematter (wt%) 32.0 40.3 27.2

These figures were obtained with the Koka-type t'lowtester manufacturedby Shimazu Mfg. Co.,

Japan.

Table 5 Coking test Comparative example Present invention No. l 2 3 4 5Proportions Coal (strongly coking coal from US, volatile 2O l0 matter19-20 wt%) (coking coal from Australia. volatile matter 40 45 40 20-23wt%) (weakly coking coal from Japan, volatile 40 S0 45 45 45 matter35-40 wt%) Pitch of the present invention (No.101)* 5 10 15 Strength ofcoke Drum index (Dl JlS, K-2l5l-6 92 76 93 91 93 Two additional testswere conducted, using the pitches obtained in runs Nos. 102 and 103,respectively, and mixing each the listed coals in the proportions listedin column 3. The Drum Index for each of these mixtures was 92.

EXAMPLE 2 Table 6 Properties of the residue from the distillation ofArabian light crude under normal pressure and having the propertiesgiven in Table 6 was placed in the apparatus described in Example 1. Theoperating conditions and material balance are shown in Table 7.

Specific gravity Fixed carbon Softening point Ash Element C analysis H N6.8 below room temperature Example 1. The coke strength, or Drum Index,was

710C) was injected into the bottom liquid, maintain- Table 7 mg thebottom liquid at a temperature of from 400 to Operational conditionsMaterial balance (wt%) 410C f 6 h Heat transfer gas Nitrogen H, 0.04 Thecracked gas and oil produced in the heat treatgfig gpj g 700C CH4 5 mentwere stripped out of the reaction vessel and a Heat transfer medium 3,C2H6 CZH L8 highly aromatic pitch was obtained in a yield of 26.5% rratet 430C C H C 6 T by weight, while the yields of gas, light oil and heavyoil a 1 0| em race nuratign of opeliation 120 Min liydmgarbon 0 were3.9%, 10.2% and 59.5% by weight, respectively. M9 8.1 ,S 0.7 Theproperties for the feed stock and the pitch product gigg 10 are shown inTable l and Table 9, respectively. L055 1 The pitch product was groundinto powder and mixed with various types of coal, and the mixture wasthen subjected to a can baking test (box test) as described inExample 1. Table 10 gives the test results. 5

Table 9 Properties of the pitch product Softening point 225C determinedto be 91. Fixed carbon 69 Benzene insoluble matter 65 wt 0 EXAMPLE 3Quinoline insoluble matter 38 wt% Using the apparatus and systemillustrated in FIG. 1, WC (ammo mm) Table 8 Properties of the distilledProperties of the pitch product oil product Specific gravity (d,) 0.920Softening point (C) 159 Flash point (C) 134 Fixed carbon (wt%) 53.1Distillation test Ash (wt%) 0.3 I.B.P. (C) 190 Element analysis 20%distilled (C) 355 C (wt%) 85.9 50% distilled (C) 410 H 6.61 80%distilled (C) 465 N 0.49 S 6.54 Element analysis 1-1/C 0.924

C (wt%) 85.30 Solvent extraction test H 12.44 Benzene insoluble 16.6 N0.20 matter (wt%) S 1.80 Quinoline insoluble 1.8 H/C 1.75 matter (wt%)Table 10 Coking tests Example 3 No 1 2 4 5 Coal Strongly coking coalfrom U.S. 20 20 0 0 10 (volatile matter 19 18 wt%) Coking coal from 4040 50 50 Australia (volatile matter 26-28) wt%) Weakly coking coal fromJapan 40 40 50 45 (volatile matter 35-40 wt%) Pitch of the presentinvention 0 l 0 5 S Coke strength, D1 91.2 91.8 82.2 81.1 92.3

(HS-K2151) 300kg/hr of Khatji vacuum residue was subjected to preheattreatment in a tubular furnace wherein the outlet pressure was l5kg/cmthe outlet temperature 475C and the dwelling time 1.3 minutes (at 350 to475C).

The preheated vacuum residue was flashed by injection into a reactionvessel where kg/hr of steam (at Table 1 l Compositions for the CanBaking Tests Example 3 Weakly coking coal from 100 90 70 50 Australia(New Deal) Pitch of the present invention 0 5 1O 30 50 Coke strength D168.9 74.3 81.5 88.7 91.4

In this example, the first step reaction (cracking) was principallycarried out in the tubular furnace and the second step reaction(poly-condensation) occurred subsequently in the reaction vessel. Thisexample shows that high temperature such as 475C may be employed in thefirst step reaction.

EXAMPLE '4 Using the apparatus andsystem illustrated in the flow sheetof the drawing, a residual oil starting material, the same as that usedin Table 1, was processed with a feed rate within the range of 100kg/hrto 300kg/hr.

The superheated steam (from source 7) was introduced into the reactor 6at 620C and at a flow rate of 30.4kg/hr. The test conditions were asfollows: T (temperatureat the exit of pre-heating furnace) 480C; T(liquid. temperature in the reaction) 420C; P (pressure at the entranceof the preheating cracking furnace)32 kglcm G; P (pressure inside thereactor) 0.1 kglcm G; O (dwelling time in the preheating ,crackingfurnance) 3.2 minutes, and O (dwelling time in the reactor) 3.5 hours.

The test yielded the following products:

By-product gas 4.6%, light oil 11.3 wt%; heavy oil 58.4 wt%; andresidual pitch 25.5 wt%. Table 12 shows the properties of theseproducts.

Table 13 gives the operating conditions for a series of tests conductedusing the system and apparatus depicted in the drawing. Case 1, as shownin Table 13, refers to the test run described above.

The pitch products obtained from each of the test runs of Table 13 weresubjected to a can baking test (box test) for the determination ofcoking strength. The mixtures used in each of these tests consisted of80 parts by weight of OS coal from USSR, which is a noncoking coal, and20 parts by weight of the pitch. The results of these tests are alsoshown in Table 13.

Table 12 Properties of products of Example 4 properties of oilComposition of gas 1i gm oil Heavy Oil roperties of pitch H 8 11.9(vol.%) C 83.5 (wt.%) 83.5 (wt.%) C 87.7 (wt.%) H 7.4 1-1 14.6 11.4 H5.77 C11 32.5 S 1.6 4.6 S 6.15 C 11 2.7 IBP 38C 212 1-1/C 0.78 SP. 230 Cl-1 15.6 20%120 325 EC. 67.0 (wt.%) C l-1., 7.5 80%196 505 B.1. 58/3(wt.%) C l-1 10.7 0.1 27.0 (wt.%) C at 11.6 Sp.Gr. 1.25

Table 13 Example 4 Operating Conditions and Yields ASE 1 2 3 4 5 6 7 8 910 11 Feed rate (Kg/H.) 101 100 102 100 103 300 300 300 300 300 300 Flowrate of superheated 30.4 50.7 25.0 18.5 5.3 120 80 80 120 120 120 steam(Kg/H.) Temperature of superheated 620 620 850 850 1600 650 750 830 630650 680 steam (T fC) Temperature at the exit 480 480 475 485 480 500 500500 485 485 485 of the preheating cracking furnace (T IC) Pressure atthe entrance of 32 33 102 105 101 29 29 28 28 '28 '28 the preheatingcracking furnace (P Kg/cmG) Pressure at the exit of the 10 11 73 72 70 33 3 4 4 4 preheating cracking furnace K [cm 6) Dwelling time 111 the 3.22.5 3.5 3.5 3.5 2.7 2.7 2.7 3.2 3.2 3.2 preheatin cracking urnace min.)Temperature at the liquid 420 380 410 385 365 430 480 510 430 430 430 inthe reactor (T C) Pressure of the liquid 0.1 0.5 0.1 0.75 0.90 2.2 2.22.2 0.3 2.9 5.8 in the reactor (P Kg/cm G) Average dwelling time 3.5 6.52.0 2.5 1.0 1.5 0.14 0.05 1.3 1.6 1.9 in the reactor (0 Hr.) Partialpressure of 167 129 198 55 58 390 545 (545) 157 445 747 hydrocarbonvapor in the reactor (Porg, mmHg) k0 13.2 2.1 3.6 2.4 8.6 8.1 9.5 7.59.2 11.9 Product yield Gas wt 4.6 7.2 8.4 8.0 15.8 5.2 9.5 4.8 5.0 6.2Light oil 11.3 10.5 12.1 12.0 23.0 11.5 12.8 11.0 13.5 17.5 Heavy oil58.4 45.9 55.2 54.9 36.5 57.7 53.0 58.5 51.6 45.4 Pitch 25.5 36.2 24.725.1 24.7 25.2 24.1 24.5 28.5 31.0 Properties of pitch Softening Point,230 128 241 232 229 229 230 unmeasu- 221 225 222 C able Table13-continued Example 4 Operating Conditions and Yields CASE 1 2 3 4 5 68 9 10 11 Fixed Carbon, w t% 67.0 58.3 69.3 66.2 68.4 67.3 68.3 74.167.8 69.0 71.0 l-I/C (atomic ratio) 0.78 0.82 0.77 0.78 0.71 0.79 0.810.62 0.77 0.78 0.75 Bttepzene insoluble, 58.3 49.2 59.2 58.6 63.2 58.060.0 72.0 59.0 61.0 64.2 W 0 Quinoline 27.0 7.4 29.1 26.1 30.3 26.5 38.059.0 26.3 31.0 42.5 insoluble, wt%

Coke Strength (Dl 92.6 92.1 91.7 93.1 92.4 93.0 90.8 72.0 92.8 92.0 90.5

The strength in case of 0S coal alone was 15.1.

"While the calculated value of k0 is 0.2, effective k0 is estimated tobe considerably larger than 0.2. The reason is the same as that of therun No. 101 in Example 1. Note: Cases 7, 8 and 11 are comparativeExamples.

In the runs of Example 4, the first step reaction (cracking) was mainlyoccurred in the preheating furnace and the second step reaction(poly-condensation) occurred in the bottom phase within the reactor.

In producing a pitch suitable for a binder, the second step reaction ismore significant than the first step reaction.

This will be appreciated by comparing cases 6 and 8, with cases 9 and11, respectively.

In case 8, the coking occurs to a remarkable extent due to too high aliquid temperature in the reactor (T,C hence a stable operation can notbe maintained. In addition, a material balance can not be obtained incase 8 since the operation is forced to shut down after a lapse of 30minutes. Moreover, the use of too high a partial pressure of hydrocarbonin the reactor (Porg, mmHg) gives rise to an increase in the oil contentin the pitch phase, hence a phase separation occurs, which producesheavy coking. Also, operation under such a high partial pressure (Porg,mmI-IG) tends to form a pitch which resembles a mixture of oil and coke,and the size of mesophase particles in the thus formed pitch become muchlarger.

The properties of such a pitch as binder (see case 11) are poor ascompared with cases 9 and 10.

The invention may be embodied in other specific forms without departingfrom its spirit or essential characteristics. The foregoing examplesare, therefore, to be considered in all respects as illustrative and notrestrictive, the scope of the invention being indicated by the claimsrather than by the foregoing description, and all changes which comewithin the meaning and range of the equivalents of the claims aretherfore intended to be embraced therein.

We claim:

1. A process for the liquid phase cracking and aromatization of areduced crude oil residuum consisting mainly of aliphatic hydrocarbonsto produce pitch having a H/C ratio of 0.4 1.1 and a non-pitch oilcontaining a major portion of aliphatic hydrocarbons, said processcomprising:

providing, in a reaction zone, a vapor phase and a continuous liquidphase, which includes said residuum, at a total pressure less than 3.0kglcm G with a liquid dwell time of 0.5 to 20 hours;

feeding a non-oxidative heat transfer medium at a temperature within therange of 400C to 2000C through and in direct contact with said liquidphase in said reaction zone to maintain said liquid phase at atemperature of 350450C, to induce a polycondensation reaction in saidliquid phase, and to strip volatile components from said liquid phase;

controlling the feed rate of said heat transfer medium to maintain thepartial pressure in mmI-Ig of organics in said vapor phase at less thanabout:

wherein T is the temperature (C) of the liquid phase within the reactionzone; and

removing a non-pitch overhead from said reaction zone and recoveringsaid pitch as the bottoms product of said reaction zone.

2. The method of claim 1 wherein said petroleum base residual oil ispreheated to a temperature of 450C 520C by passing said residual oilthrough a tubular system where the outlet temperature is within therange of 450C to 520C and the outlet pressure within the range of 0 tokg/cm G, maintaining the dwell time of the residual oil in the tubularsystem within the range of 0.5 to 5.0 minutes.

3. The method of claim 1 wherein said non-oxidative gaseous heattransfer medium is selected from the group consisting of nitrogen,argon, steam, hydrogen and hydrocarbon gases.

4. The method of claim 1 wherein said liquid phase temperature and saidpartial pressure of organics are within the operating region designatedcondition suitable for pitch formation in FIG. 2.

1. A PROCESS FOR THE LIQUID PHASE CRACKING AND AROMATIZATION OF AREDUCED CRUDE OIL RESIDUUM CONSISTING ESSENTIALLY OF ALIPHATICHYDROCARBONS TO PRODUCE PITCH HAVING A H/C RATIO OF 0.4 - 1.1 AND ANON-PITCH OIL CONTAINING A MAJOR PORTION OF ALIPHATIC HYDROCARBONS, SAIDPROCESS COMPRISING: PROVIDING, IN A REACTION ZONE, A VAPOR PHASE AND ACONTINUOUS LIQUID PHASE, WHICH INCLUDES SAID RESIDUUM, AT A TOTALPRESSURE LESS THAN 3.0 KG/CM2G WITH A LIQUID DWELL TIME OF 0.5 TO 20HOURS; FEEDING A NON-OXIDATIVE HEAT TRANSFER MEDIUM AT A TEMPERATUREWITHIN THE RANGE OF 400*C TO 2000*C THROUGH AND IN DIRECT CONTACT WITHSAID LIQUID PHASE AT A TEMPERATURE OF ,TO MAINTAIN SAID LIQUID PHASE ATA TEMPERATURE OF 350*-450*C, TO INDUCE A POLYCONDENSATION REACTION INSAID LIQUID PHASE, AND TO STRIP VOLATILE COMPONENTS FROM SAID LIQUIDPHASE; CONTROLLING THE FEED RATE OF SAID HEAT TRANSFER MEDIUM TOMAINTAIN THE PARTIAL PRESSURE IN MMHG OF ORGANICS IN SAID VAPOR PHASE ATLESS THAN ABOUT; 1.03 X (10)11 X E- (1200/R+220) WHEREIN T IS THETEMPERATURE (*C) OF THE LIQUID PHASE WITHIN THE REACTION ZONE; ANDREMOVING A NON-PITCH OVERHEAD FROM SAID REACTION ZONE AND RECOVERINGSAID PITCH AS THE BOTTOMS PRODUCT OF SAID REACTION ZONE.
 2. The methodof claim 1 wherein said petroleum base residual oil is preheated to atemperature of 450*C - 520*C by passing said residual oil through atubular system where the outlet temperature is within the range of 450*Cto 520*C and the outlet pressure within the range of 0 to 150 kg/cm2G,maintaining the dwell time of the residual oil in the tubular systemwithin the range of 0.5 to 5.0 minutes.
 3. The method of claim 1 whereinsaid non-oxidative gaseous heat transfer medium is selected from thegroup consisting of nitrogen, argon, steam, hydrogen and hydrocarbongases.
 4. The method of claim 1 wherein said liquid phase temperatureand said partial pressure of organics are within the operating regiondesignated ''''condition suitable for pitch formation'''' in FIG. 2.